A number of technologies such as ultrasound and tomography are available for three-dimensional imaging. In medical imaging, for example, an imaging system captures a three-dimensional image from a patient for the analysis of bodily tissue. Such systems display the images on computer monitors as two-dimensional pictures.
With a two dimensional display, there are generally at least two approaches to displaying three-dimensional images. Two perpendicular views can be displayed side-by-side, thereby aiding in understanding a three dimensional structure. Another way of showing a three dimensional structure is to show a series of two dimensional views sequentially, allowing a user to see each one in turn to aid in understanding three dimensional tissue structures. Some such displays allow a user to progress through a series of two dimensional images through use of a mouse or keyboard. Where each of the images has an axis in common, the display may appear to rotate as a user uses a keyboard or mouse to increment through the views. In this way, a user can see information about a feature in a patient's tissue (e.g., a plaque) in three dimensions.
A system operator relies on the ability to see information about tissue in three dimensions to use the imaging system most effectively. For example, where a scan reveals a medically significant feature, an operator may need to scroll through a series of views to determine the location of the feature. Since features in biological tissue have irregular shapes, a user may need to see different views to understand the extent of the feature. For example, where a plaque lies along an artery, a system operator may need to consult several different longitudinal views (i.e., cross sections along the artery) to determine the full length of the affected area. This gives the information needed to set up a follow up imaging scan to take a “close up” picture of the plaque.
Since scrolling through different longitudinal views requires the user's interaction (e.g., by using arrow keys or a computer mouse) a user's hands are not free to set up a subsequent “close up” scan operation while scrolling through the two dimensional images. To set up, for example, a start and stop position for a “close up” scan, a user must scroll through the rotating longitudinal display and remember the start and stop positions and then enter start and stop positions from memory. Since it is difficult to control the operation of image capture while viewing a series of longitudinal images, capturing a close-up view of a medically significant feature is imprecise and involves some guesswork or trial and error. As a result, high resolution scans of medically significant features are sometimes directed at the wrong portions of tissue, making proper medical analysis difficult.